Method of recovering acid from acid sludges



SEARCH @t E Patented May 4, 1937- UNITED I STATES PATENT OFFICE METHODOF RECOVERING ACID FROM ACID SLUDGES Chester L. Read, Jersey City, andPaul J. Harrington, Westfield, N. J., assignors to Standard OilDevelopment Company, a corporation of Delaware No Drawing.

4 Claims.

This invention relates to the treatment of acid sludges obtained by theaction of sulfuric acid on petroleum oils or distillates for recoveringsulfuric acid therefrom, and particularly relates to the treatment ofviscous acid sludge, i. e., acid sludge obtained by the action ofsulfuric acid on mineral oils.

In the treatment of crude oils, lubricating oil distillates andmedicinal oils with sulfuric acid, sludges are formed, especially fromthe first increments of the acid applied, which are very viscous. Thesesludges are frequently so viscous as to make handling difiicult orimpossible. Separation of tar and weak acids from these sludgesApplication December 27, Serial No. 704,089

in the first one or two treats with sulfuric acid has been removed. Thislow viscosity sludge obtained in the treatment of refined oildistillates, naphtha distillates, and heavier mineral oil with sulfuricacid is readily separated on the addition of water and heating and anacid oil of low viscosity is obtained. This acid oil is of low viscosityso that a relatively small amount of it has a large effect in loweringsludge viscosity on fiuxing, and it does not coke on contacting with aheavy acid sludge. A specific example is as follows:

The acid sludge, derived from the treatment of crude distillate with 20%fuming sulfuric acid is also very troublesome and the low yield of forthe production of medicinal oils is very visl5 acid and high acidity andviscosity of the tar cous and is most difficult to pump. The separamakeseparation very unattractive. Efforts have tion of this sludge withwater is difficult and been made in the past to flux heavy sludgesberesults in very low acid recovery and the forma-' fore moving orseparating them, but the use of tion of a high acid content fuel whichmust be the fluxing stocks formerly tried has the followheated andfluxed with a fuel oil before burning. ing disadvantages: One volume ofthis sludge is fiuxed with one 1. Cracked products, such as crackingcoal tar, volume of a naphtha distillate acid separated oil etc., whenfluxed with heavy sludges result in (which had been previously separatedby dithe formation of carbonaceous solids which tend luting with water asludge form by treating a to clog burners used to burn the resultingsepanaphtha distillate with strong sulfuric acid) with 5 rated oil. theresult that the fluxed stock obtained is very 2. Crude pitches are ofrelatively high viscosity mobile and may be easily pumped and handled.at the low temperatures necessary when han- This fluxed sludge may thenbe diluted with water dling sludges, and usually contain enough crackedand a 70 to 80% acid recovery obtained in the materials to cause theformation of carbonaseparated aqueous layer. The oil layer obtainedceous solids on contacting with the sludges, with may be easily handledand has a low acid conthe result that it is difficult to burn theresulting tent, permitting it to be burned without further separated oilby means of oil burners. fluXing.

3. Light crude fractions are too valuable to Alternatively, in treatinga heavy crude distildegrade to acid oil and tar. Because of its latewith strong sulfuric acid in a number of acid content and the nuisanceassociated with treats, the sludge obtained in the first or first itscombustion, acid oil has a value far below and second treats is viscous.The subsequent that of fuel so that even crude pitch or cracking treatswith strong sulfuric acid yield relatively coal tar would suffer adegradation when fluxing low viscosity sludges. These relatively low viswith heavy sludges. cosity sludges are separately diluted with water, 40

An object of this invention is to provide a heated, and on settlingseparate into layers of method of treating heavy acid sludges so thatacid oils of low viscosity and dilute acids. handling and separation arefacilitated without The viscous sludge obtained in the first or firstformation of coke and without greatly degradand second acid treats. isthen mixed with the ing the fluxing stock. separated acid oils thusobtained, diluted with A further object of this invention is to providea method of treating heavy acid sludges so that a greater amount ofsulfuric acid may be recovered from the heavy acid sludges.

water, heated, and on settling readily separates into layers of an acidoil and dilute sulfuric acid. This separated acid oil similarly may beeasily handled and has a low acid content,

According to this invention, in the acid treatpermitting it to be burnedwithout further flux ing of refined oil distillates and naphthadistiling. lates a relatively low viscosity sludge is formed. Inasmuchas the above description and ex- Likewise, a relatively low viscositysludge is obamples have been given merely for the sake of tained in thetreatment of a heavier mineral oil illustration and not for the purposeof limiting with sulfuric acid after the viscous sludge formed theinvention thereto, it is intended to claim all inherent novelty in theinvention as broadly as the prior art permits.

We claim:

1. The process of treating acid sludges obtained from the acid treatmentof petroleum oils, which comprises adding to a relatively high viscositysludge obtained by a sulfuric acid treatment of a petroleum oil, a lowviscosity acid oil that has been separated by diluting with water a lowviscosity acid sludge obtained by a sulfuric acid treatment of apetroleum oil, diluting the mixture of oil and sludge with water,treating, settling and separately Withdrawing dilute sulfuric acid andoil.

2. The process of decomposing high viscosity acid sludges whichcomprises fiuxing a sludge obtained by the treatment of petroleum oilWith fuming sulfuric acid with an acid oil that has been separated,after dilution with water, from a low viscosity sludge obtained bytreating a light petroleum distillate with sulfuric acid, diluting themixture of sludge and acid oil thus obtained With water and separatelyremoving dilute sulfuric acid and acid oil.

3. The process of treating acid sludges, which comprises diluting anacid sludge obtained from the sudfuric acid treatment of a heavypetroleum oil, with a low viscosity acid oil that had been separated bydiluting with water a low viscosity sludge obtained by the sulfuric acidtreatment of a petroleum oil, diluting the mixture of sludge and acidoil with Water, heating, settling and separately withdrawing a diluteacid and an acid

